Influxdb - Write error: 400

I hope you can help me with my problem.
For 2 days now, a sensor hasn’t given any values from Grafana.
I found an influx error in the logfile.
Unfortunately the error message doesn’t tell me what possibilities I have to fix the error.

  • Is this a crash of the database for this entry?
  • Is there a possibility to repair the database?
  • Or is there another way to fix the error?
    Thanks for your help.

2020-06-09 23:31:32 ERROR (InfluxDB) [homeassistant.components.influxdb] Write error: 400: {“error”:“partial write: unable to parse ‘kWh,domain=sensor,entity_id=energy_spent_poolpumpe friendly_name_str="energy_spent_poolpumpe",icon_str="mdi:chart-histogram",source_str="sensor_verbrauch.poolpumpe",value=nan 1591738228934721024’: invalid number dropped=0”}

Home Assistant: 0.110.6
InfluxDB: 3.7.1